How to Replace a 1998 Audi Thermostat


1. Remove the radiator hose clamp that secures the top radiator hose to the thermostat housing. Do this by prying the clamp loose with a pair of pliers. With the clamp loose, pull the hose off the thermostat housing. Hold the hose vertical to drain the radiator fluid back into the radiator. Push the radiator hose off to the side.
2. Remove the bolts that secure the thermostat housing to the intake manifold of the Audi with a wrench. Do not discard the bolts. Use them when reattaching the housing.
3. Lift the thermostat housing off the engine to expose the thermostat. Inspect the bottom of the thermostat for the thermostat gasket. If it is not on the thermostat housing, it will be on the base of the intake manifold. Remove the old thermostat gasket and place a new one on the base of the thermostat housing.
4. Pull the old thermostat out of the intake manifold and replace it with a new one. The end marked 'top' should face upward and the end with the spring in it must face downward.
5. Place the thermostat housing on top of the thermostat gasket and bolt it into place using the old bolts.
6. Slide the radiator hose onto the thermostat housing and secure it with the clamp. If the clamp suffered damage during the removal process, replace it with a band clamp.